ABSTRACT
A portable rectal near infrared (NIR) scanning polarization imaging unit with an optical fiber-based rectal probe, designated as a Photonic Finger (PF), was designed, developed, built and tested. PF was used to image and locate the three dimensional (3D) positions of abnormal prostate tissue embedded inside normal prostate tissue. An inverse image reconstruction algorithm, namely Optical Tomography using Independent Component Analysis (OPTICA) was developed to unmix the signal from targets (cancerous tissue) embedded in a turbid media (normal tissue) in the backscattering imaging geometry. The Photonic Finger combined with OPTICA was ex vivo tested to characterize different target(s) inside different tissue medium, including cancerous prostate tissue embedded inside large pieces of normal tissue. This new developed instrument, Photonic Finger, may provide an alternative imaging technique, which is accurate, of high spatial resolution and non-or-less invasive for prostate cancers screening.
Subject(s)
Early Detection of Cancer , Infrared Rays , Photons , Prostate/pathology , Prostatic Neoplasms/diagnosis , Tomography, Optical/instrumentation , Tomography, Optical/methods , Algorithms , Animals , Chickens , Computer Simulation , Female , Humans , Male , Mammary Glands, Animal/pathologyABSTRACT
We have measured UV fluorescence excited through two-photon absorption from native chicken tissue, using 600-nm, 500-fs pulses from a R6G dye laser. The observed emission signal was found to depend quadratically on the excitation intensity. The two-photon excitation-induced fluorescence spectrum is attributed to tryptophan residues in proteins.
ABSTRACT
15-THz trains of a few-tens-of-femtoseconds optical pulses were generated by modulation instability oscillation in a colliding-pulse mode-locked dye laser. A repeatable and stable modulation instability regime was obtained with the laser operating in the anomalous-dispersion regime and with a low saturable-absorber concentration. Autocorrelation measurements indicate that subpulses were completely separated in real time. Variations of the modulation with the pump power and the amount of dispersion in the cavity are in good agreement with modulation instability theory.
ABSTRACT
A new method for femtosecond pulse generation using a binary energy-transfer dye mixture for the gain medium in a novel linear ring colliding-pulse mode-locked dye-laser configuration is reported. Pulses of 30-fsec duration and 18.7-nm spectral width are routinely generated.
